I think the easiest way to resolve this is for you to answer this: Do you like Alexandre Dumas? Have you read and enjoyed The Three Musketeers?
The Phoenix Guards books are Brust's homage to Dumas, and while they're in no way, shape or form simply a ripoff or a fantasy re-hash of the Musketeer novels, they're very heavily influenced by Dumas stylistically. I think that they stand well enough on their own that even someone not crazy about Dumas ought to give them a look - on the other hand, if you explicitly dislike Dumas' stuff, they're probably not the books for you.
The Taltos books, on the other hand, use a completely modern writing style, and are - in my opinion - a much faster read. Taltos, Dragon and Jhereg are also fairly short books, at under 300 pages, so you can find out if you like Brust rather quickly if you pick up one up.